This invention relates generally to systems for controlling power transistors, and more particularly, to a method and circuit arrangement for controlling the conductive and nonconductive states of power field-effect switching transistors.
It is known that the time required during the switching of a field-effect transistor between its conductive and nonconductive states is determined by the charging and discharging time of the gate-source capacitance of the FET. Such a gate-source capacitance, particularly in power FET's, assumes considerable values. It is also known that power dissipation by a transistor during switching operations is minimized by reducing the switching times to as short a duration as possible. Short switching times have been achieved by utilizing driving circuits which supply relatively large pulse currents. Thus, commercially available drive circuits achieve the desired large pulse currents by utilizing separate auxiliary voltage sources. Such auxiliary voltage sources, however, are relatively expensive.
It is, therefore, an object of this invention to provide a method for driving a power field-effect switching transistor by the use of large pulse currents, without the need for separate auxiliary voltage sources.
It is a further object of this invention to provide drive circuitry for controlling the switching between conductive and nonconductive states of a power field-effect switching transistor by supplying large pulse currents thereto, without requiring separate auxiliary voltage sources.